git: 9b6930c6eadb - stable/13 - kasan: disable kasan_mark() after a violation

The branch stable/13 has been updated by kevans:

URL: https://cgit.FreeBSD.org/src/commit/?id=9b6930c6eadb74c0261e257d6543d9f640188733

commit 9b6930c6eadb74c0261e257d6543d9f640188733
Author:     Mitchell Horne <mhorne@FreeBSD.org>
AuthorDate: 2022-09-27 16:01:02 +0000
Commit:     Kyle Evans <kevans@FreeBSD.org>
CommitDate: 2022-11-02 17:02:24 +0000

    kasan: disable kasan_mark() after a violation
    
    Specifically, when we receive a violation and we're configured to panic,
    kasan_enabled gets unset before we descend into panic().  At this point,
    there's no longer any reason to allow marking as kasan_shadow_check() is
    disabled -- we have some inherent risk of faulting or panicking if the
    system's in a bad enough state with no benefit.
    
    Reviewed by:    markj
    Sponsored by:   Juniper Networks, Inc.
    Sponsored by:   Klara, Inc.
    
    (cherry picked from commit f2963b530e17c5eff66bc5f4860b1cd224d3d033)
---
 sys/kern/subr_asan.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/sys/kern/subr_asan.c b/sys/kern/subr_asan.c
index 70f7e11ef8f6..bdb7fc3da368 100644
--- a/sys/kern/subr_asan.c
+++ b/sys/kern/subr_asan.c
@@ -251,6 +251,9 @@ kasan_mark(const void *addr, size_t size, size_t redzsize, uint8_t code)
 	size_t i, n, redz;
 	int8_t *shad;
 
+	if (__predict_false(!kasan_enabled))
+		return;
+
 	if ((vm_offset_t)addr >= DMAP_MIN_ADDRESS &&
 	    (vm_offset_t)addr < DMAP_MAX_ADDRESS)
 		return;